To do this part of the lesson, download this Geometer's Sketchpad file.

Open the Sketchpad file and follow the following steps.

DATA: 11.5 cm bolt circle diameter - 5 bolt pattern

In this section, we will get more practice finding Bolt Circle Diameters and Chord Lengths.
STEP 1: Measure <EAD 

STEP 2: Without using the computer, what is the measure of <EAX ?

STEP 3: Find the SIN of <EAX

STEP 4: Find half of the Bolt Circle Diameter

STEP 5: Multiply your answer to STEP 4 and STEP 3

STEP 6: Double click the SHOW CHORD LENGTH Button.
What is the measure of the Chord Length ED ?

STEP 7: Compare your answer to STEP 6 with your answer to STEP 5

STEP 8: Describe the procedure of finding the Chord Length if the Bolt Circle Diameter is known.

DOUBLE CLICK THE HIDE BCD BUTTON.

STEP 1: Write your answer from STEP 3 above

STEP 2: Find half the Chord Length

STEP 3: Divide your answer to STEP 2 by your answer to STEP 1

STEP 4: Multiply your answer to STEP 3 by 2

STEP 5: Double click the SHOW BCD BUTTON. What is the measure of the Bolt Circle Diameter?

STEP 6: Compare your answer to STEP 5 with your answer to STEP 4

STEP 7: Describe the procedure of finding the Bolt Circle Diameter if the Chord Length is known.

DOUBLE CLICK THE HIDE CHORD LENGTH BUTTON.

Now, double click the CHANGE CIRCLE SIZE BUTTON.

Make the circle somewhere between 8 and 10 cm and then click the mouse.

For your circle size, find the CHORD LENGTH

Again, double click the CHANGE CIRCLE SIZE BUTTON. Make the circle somewhere between 6 and 8 cm.

For your circle size, find the CHORD LENGTH

DOUBLE CLICK THE SHOW CHORD LENGTH BUTTON.

DOUBLE CLICK THE HIDE BCD BUTTON.

Again, make the circle somewhere between 8 and 10 cm and then click the mouse.

For your circle size, find the BOLT CIRCLE DIAMETER

Double click the CHANGE CIRCLE SIZE BUTTON and make the circle somewhere between 6 and 8 cm.

For your circle size, find the BOLT CIRCLE DIAMETER